oven to 350 degrees F (177 degrees C) and place rack in center of oven. Line
a baking sheet with parchment paper.
In the bowl of
your electric mixer (or with a hand mixer), beat the butter and sugar
until light and fluffy (2-3 minutes). Add the eggs and egg yolk, one at a
time, mixing well after each addition. Beat in the vanilla extract. Scrape
down the sides of the bowl as needed.
In a separate bowl, whisk together the flour, baking powder, salt, and cocoa
powder. Add to the butter mixture and beat until incorporated. Stir in the dried cranberries and white chocolate
Transfer the dough to a floured surface and divide it in half. Form each half into a log
10 inches (25 cm) long. Do this by rolling the dough back and forth into a
cylinder shape with floured hands. Transfer the logs to the baking sheet,
spacing them well apart (width-wise on the pan), and pat to even the shapes.
Bake until firm to the touch, about 25 - 30 minutes (logs will spread during baking). Remove from
the oven, place on a wire rack, and let cool for about 10 minutes.
Using a long spatula transfer the logs to a
cutting board. Using a serrated knife, cut the logs into slices
about 3/4 inch (2 cm) thick on
the diagonal. Arrange the slices on the baking sheet and bake on
about 8 - 10 minutes. Turn the slices over and bake until crisp and dry, about
8 - 10
minutes longer. Remove from oven and let cool on wire rack.
24 - 30 biscotti.